It was scheduled to leave DTW at 10:20pm on the 3rd but was initially delayed due to an issue with the number 2 engine. It ended up leaving at 1:42am on the 4th and subsequently diverted to JFK because of a different issue with an airspeed indicator. There was an equipment change and the crew was replaced. The flight left JFK at 7:56am and arrived in LHR about 9 hours late.